I. Field of the Invention
The present invention relates to ergonomic adaptations for devices that serve as tools, particularly handles to tools, as well as support devices such as crutches. The devices are provided with auxiliary handling additions of various configurations having a variety of geometries. These include hand grips, foot pads, forearm supports, etc., in order to facilitate the ergonomic, secure and convenient function of devices, including, but not limited to shovels, snow scrapers, rakes, brooms, hand grips, crutches, lawn-edgers, paint-rollers, squeegees, line-markers, wheeled service jacks, hand trucks and dollies, and similar tools.
II. Related Art
Much manual labor is performed using tools whose designs have remained relatively static for tens, if not hundreds, of years. Some of the most common acts which continue to be performed by a wide variety of individuals are shoveling, sweeping, raking and wheeling/moving rolling objects. Many of those who perform these tasks are experienced and practiced in the use of the appropriate tools and proper techniques. Nevertheless, injuries are commonplace, partly because many of the tasks are performed sporadically or occasionally by individuals not specifically conditioned or educated to use the tools in a manner to avoid such injuries, and partly because the tools themselves are simply not properly engineered to reduce strain and better suit the ergonomic requirements of human users.
In the case of generally straight-handled tools such as shovels, rakes and push brooms, most handle designs have taken a two-handed approach, requiring not only two functioning arms and wrists, but also relying heavily on a user's back to transfer and mediate forces from one hand to the other hand. The particular combination of forces presented through the two hands is what performs the work, using the tools. In most cases, the body struggles to exert force at locations some distance from the body, which often results in muscle strain, pinched nerves and other injury.
Another issue with most of these conventional tools is that for many uses, one must perform fine control and coarse strength muscular actions simultaneously using the same wrists or arms. For example, while scraping or shoveling snow, one must typically retain a firm grip to control the orientation of the shovel, while exerting considerable force to push the scraper or shovel into snow or ice. Likewise, when raking, one must pull back the tool with the dirt, gravel or leaves being raked, while maintaining a tight grip on the shaft. It is believed that the probability of muscle injuries is increased when the same muscle groups are required to perform both types of activities at the same time.
Alternative handle designs have been devised which have attempted to address some of these problems. An early concept is shown in U.S. Pat. No. 120,607, issued to Frank Allsip in 1871. Allsip devised an auxiliary handle for attachment to shovels, forks and the like, which attached to the upper handle shaft and extended above the tool head near the point of attachment to the straight handle. This provided a hand grip location closer to being above the center-of-gravity of the loaded tool head, thereby reducing back strain on a user picking up, carrying or throwing the load. Because his auxiliary handle was attached only at one point to the tool, itself, however, the rotational stability of the load was less than optimal and controlling the pitch or angle of the tool head was possibly actually made more difficult as it relied on the user gripping the upper auxiliary handle tightly and attempting to twist it. Nevertheless, Allsip's design remains of interest as an early attempt to improve the ergonomics of such tools.
Various other subsequent innovations have led to a series of accessory handles designed to fasten to traditional straight handles at some distance from the tool head, allowing the user to bend or reach less in order to obtain a grip closer to the lower end of the tool. Although they represent some improvement and some of these continue to be recommended or to be used, several important drawbacks remain. To date, these designs fail to locate the auxiliary handle close to the effective center-of-gravity of the loaded tool head and they all fail to provide sufficient strength and stability at the hand grip.
In addition, fixed forearm supports have been provided with or without an upright handle to allow some operations to be performed one-handed. Unfortunately, these designs make it difficult for one to switch arms and/or they do not enclose the forearm, thereby forcing the user to exert more effort to orient and control the tool handle.
There remains a definite need to provide an ergonomic auxiliary tool device that overcomes the shortcoming of previous devices.